The Devotion of Suspect X

The Devotion of Suspect X is a crime novel by the Japanese writer Keigo Higashino, published in Japanese in 2005 under the title Yogisha X no Kenshin. It follows a reclusive mathematics teacher who secretly loves his neighbor and, after her abusive former husband is killed when he attacks her and her daughter, helps the two women cover up the killing, arranging an elaborate alibi built on his own mathematical precision. The investigation that follows becomes a contest of intellect between the teacher and a physicist who assists the police and has known him since university, each aware of the other's ability, so that the novel's suspense lies less in the killer's identity, known to the reader from the start, than in whether the teacher's scheme can withstand his old rival's scrutiny. Widely regarded as Higashino's most acclaimed novel, it won the Naoki Prize and the Honkaku Mystery Award in Japan, was a finalist for the Edgar and Barry Awards in English translation, and has been adapted into film multiple times across different countries.